Abstract: A process for making hollow composite structures or vessels which includes the steps of: A) heating a mixture of thermoplastic matrix and reinforcing fibres wrapped over a rigid or semi-rigid thermoplastic liner or bladder above the melting point of the thermoplastic composite matrix outside of a moulding tool; B) transferring the heated assembly to a mould that is maintained below the melting temperature of the thermoplastic matrix of the composite; C) closure of the mould and application of internal fluid pressure to the liner or bladder to apply pressure to the thermoplastic matrix and reinforcing fibres; D) optionally the use of a special coupling system for rapid connection of the internal pressure; E) cooling of the liner or bladder and thermoplastic matrix and reinforcing fibre assembly in contact with the cold or warm mould while consolidation of the assembly occurs; F) opening of the mould and removal of the finished assembly.

Abstract: The invention relates to a method for producing a composite material (33) consisting of reinforcing elements (29) and a thermoplastic polyamide, said method permitting high-speed production with continuous process control, using simple equipment. The method is characterized by the following steps: the supplied reinforcing elements (29) are impregnated with a lactam melt (11) that is activated for anionic polymerization, at a temperature at which the activated lactam melt (11) does not polymerize; the impregnated reinforcing element (30) is heated and polymerized in a heating unit (17) without passing through a heated die and in an essentially contactless manner; the resultant hot polymerized composite material (31) is cooled in a cooling unit (18).